Evaluation of Relationship Between Yield and Agronomic Traits in Some Sesame Genotypes Using Factor Analysis

Sesame (Sesamum indicum L.) is an annual plant belonging to the Pedaliaceae family with a long agricultural history, which is mostly grown as an oil crop in tropical regions and is resistant to drought stress. This Crop is grown in Iran on an area of about 42,000 hectares with an average yield of 690 kg per hectare. The knowledge of the relationship between crop traits and performance is of great importance in agronomic research. Selecting the desired cultivars and determining the cause and effect relationships between traits allows the breeder to select the most appropriate plant traits to increase yield.

In this experiment, 12 sesame genotypes including commercial, local cultivars and line were evaluated. The experiment was conducted in the research farm of the Faculty of Agriculture of Persian Gulf University, Bushehr, located eight kilometers southeast of Barazjan city. The agricultural climate of the region has very hot, dry and long summers. The experiment was conducted in a randomized block design with three replications. Principal Components Analysis and Factors Analysis were used for reduction of data dimensions and better and easier interpretation of data and determination of hidden factors affecting performance.

All studied traits were statistically different. The highest amount of 1000 seed weight belongs to Behbahan (3.4 gr), Abadan (3.36 gr) and Dashtestan 2 (3.3 gr) landraces. The highest number of seeds per capsule, Plant height, number of branches and number of fertile branches were observed in Abadan, Dashtestan 5, Dashtestan 2 and (Barazjan and Abadan) genotypes, respectively. Abpakhsh, Ardakan Yazd, Barazjan and Dashtestan 5 landraces had a number of days to maturity than the others. This trait had high heritability and low genetic advances. In order to reduce the dimensions of the data, better and easier interpretation of them and to determine the hidden factors, Factor Analysis was done with varimax rotation. Three factors were extracted. According to the amount of influential traits in each factor, the first, and second factors were named yield potential and morphologic, phenology factors, respectively. In general, it can be concluded from the results that the yield and phonological traits can be important indicators for the evaluation and selection of sesame cultivars. According the Principal Components Analysis based on the correlation matrix ,76% of the total variations were estimated by three main components. As a result, it can be said that the selection based on the first component will lead to the genotypes with high yield, and the selection based on the second component will lead to the genotypes with late maturity characteristics. In order to determine the grouping of genotypes, cluster analysis was used and based on the three indices RMSSTD, False T2 and False F, four distinct groups were recognized. The results of cluster analysis did not show any relationship between the geographic and genetic distribution of genotypes.

The results showed that the studied genotypes were different according the studied traits. Because selection of genotypes with high yield is considered important in plant breeding programs, genetic parameters were calculated. The high level of genetic improvement and heritability for the traits number of capsules per plant, number of seeds per capsule, seed yield, number of fertile branches and harvest index indicate the possibility of selection with an intensity of 5% in the next generation of selection. The results of Factor Analysis indicated the importance of yield and phenology traits in the selection of desirable genotypes in sesame.